JPS59174634A - Metal-plated polyamide molded product - Google Patents

Abstract

PURPOSE:The titled composition that contains a specific wollastonite, thus showing both good appearance and high plate adhesion, and having high heat resistance, mechanical strength and toughness. CONSTITUTION:Wollastonite, which has average particle size of 0.5-4.0, preferably 0.5-2.6 microns (as the 50% middle value according to the sedimentation balance method) less than 4wt%, preferably less than 3wt%, weight loss on roasting at 1,000 deg.C, is added to polyamide in an amount of 15-60wt%, preferably 30-50wt% and the resultant polyamide is formed and plated in a known manner. The product of formed polyamide is more stabilized by selecting the content x in wt%, average particle size Z in microns and the relative viscosity of polyamide y so that they satisfy equations I and II. When the relative viscosity of the polyamide is out of the above range, the plate adhesion largely fluctuates by a small variation in forming conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to metal-plated polyamide moldings.

More specifically, the present invention provides a metal-plated polyamide molded product that has excellent heat resistance, mechanical strength, rigidity, appearance, and plating adhesion.

Conventionally, resin plated products have been mainly manufactured by etching ABS resin with a mixture of chromic acid and sulfuric acid and then plating, and have been widely used in automobiles, home appliances, and miscellaneous goods parts.

Since its properties are not very high, it is mainly used for decorative purposes. In recent years, with the rise in energy costs, there has been an increasing need to reduce the weight of automobiles, and even metal-plated parts that require heat resistance, mechanical strength, and rigidity have become targets for plastics.

Therefore, it has not yet been possible to satisfy the requirements for superior reinforcement in heat resistance, mechanical strength, and rigidity.

That is, even if the appearance is good, the adhesion strength is extremely low near the opening (hereinafter referred to as the gate) where the adhesion strength is insufficient. In addition, products with high adhesion strength have an unsatisfactory appearance,
Therefore, the current situation is that its range of use is limited.

Therefore, in order to obtain a metal-plated polyamide molded product having an ABS resin resin appearance and excellent adhesion strength, the inventors of the present invention decided to add wollastonite, among various inorganic powders, to the polyamide. Although the goal of achieving a certain culm degree was achieved, it was discovered that subtle differences in the grain size and type of wollastonite caused large differences in the appearance and adhesion strength of the metal plated part. It was discovered that there is a correlation between the content and the relative viscosity of polyamide, and the present invention was finally completed.

That is, the present invention is a metal-plated polyamide molded product, which has an average grain size of 0.5 to 4.0 μm in the polyamide molded product excluding the metal-plated portion, and has a weight loss (hereinafter referred to as ignition loss) upon firing at 1000°C. ) is a metal-plated polyamide molded product characterized by containing 15 to 60% by weight of wollastonite having a weight coefficient of 4.0 or less.

The average particle size of the wollastonite is measured by the sedimentation balance method and is expressed as a median particle size of 50 cm.
Heat-treated for 30 minutes to remove moisture.1. weight after (W,
) was measured, and then the weight (W2) after ignition treatment at 1000°C for 30 minutes was measured, and w, -w, 7 w
, x 1o O, (weight factor).

It is.

The polyamide used in the present invention is a self-polycondensate of lactam, a polycondensate of diamine and dibasic acid, a self-disarmament product of ω-amino acids, or a copolymer thereof, such as nylon 6, nylon 11, nylon 6. 6. Nylon 6
．． Nylon 6 and nylon 6.6 are suitable in terms of heat resistance, mechanical strength, and rigidity, but are not particularly limited. It may also contain various additives commonly used for modifying polyamides, such as heat-resistant anti-aging agents, weathering agents, nucleating agents, mold release agents, pigment impact modifiers, and the like.

In the present invention, the wollastonite contained in the polyamide is mainly composed of calcium metasilicate (CaFJiO8), but depending on the place of production, it may contain aluminum oxide (A90) and iron oxide (Fe0=) as impurities.
F*, O,), calcium carbonate (caco,), calcium hydroxide (Cα (OR3m), magnesium oxide, when used as a reinforcing agent for plating polyacid, calcium carbonate and calcium hydroxide in impurities improve plating properties, In particular, it has a negative effect on surface gloss and adhesion.

Therefore, it is necessary to use wollastonite in which the amounts of calcium carbonate and calcium hydroxide contained as impurities in wollastonite are below a certain value. The content of calcium carbonate and calcium hydroxide in wollastonite is determined by the weight loss rate after heating wollastonite at 1000°C (1 polyamide molded product with stable plating properties is obtained only when the weight loss rate is below 100°C). If the ignition loss exceeds 4 weight coefficients, parts that are difficult to etch will occur near the gate of the molded product, and calcium carbonate in wollastonite will react with acid during the cultural plating process, producing a large amount of carbon dioxide gas. However, the plating surface gloss and adhesion strength are significantly reduced.

Further, in the present invention, the above-mentioned wollastonite is preferred.

On the other hand, if the average particle size is less than 0.5 μm, the holes in the recesses formed by etching will be too small, and the anchoring effect for improving plating adhesion and b degree will be undesirable.

It weighs 50 pounds. If the content is less than 15% by weight, the heat resistance, mechanical strength, rigidity, etc. of the polyamide will be insufficient, and if the content exceeds 60% by weight, the molded product will become brittle and the plated surface gloss will decrease. Undesirable.

The method of incorporating the wollastonide specified in the present invention into the polyamide includes a method of blending a predetermined amount of wollastonite into polyamide pellets using a tumbler, etc., and extruding the mixture using a single-screw or twin-screw extruder to pelletize it again. Any method may be used as long as wollastonite is uniformly dispersed in the polyamide, such as adding wollastonite before or during polymerization.

In addition, in order to more stably obtain the polyamide molded product of the present invention, the content of wollastonite and the average particle size are as follows (
It is desirable that the following equation be satisfied.

2.0≦V≦-0,0156, +3.3...
...... Open - (1) 2.0 ≦F ≦0.0
617 Z +2.9 ・・・− に・−==・−・−
-----(Ill)The relative viscosity of the polyamide is JI
According to S standard 6810, 96 drops of polyamide 200
．． This is the value measured at 20'C after dissolving in 200D of V5 sulfuric acid.

If the relative viscosity of the polyamide is less than 2.0, even if wollastonite or other fillers are blended, the moldability will be poor, the mechanical properties of the resulting molded product will decrease, and it will become brittle.
Furthermore, the plating adhesion strength also decreases, which is not preferable.

On the other hand, if the relative viscosity of polyamide exceeds the value shown in formula (1) and +11 above, even a slight change in molding conditions will cause large variations in plating adhesion strength, and in particular the adhesion strength near the gate of the molded product will partially change. During actual use, the plating layer near the gate swells, causing problems with the appearance of the plating. Furthermore, even if the optimum molding conditions are set, it is difficult to consistently obtain a good molded product, and variations in plating adhesion strength become large, and the plating layer near the gate may swell.

Next ((For the method of molding the polyamide having the above-mentioned structure and plating it with metal, a conventionally known method can be adopted.
Methods for etching polyamide moldings before metal plating include (1) immersing the polyamide molding in chromic acid/sulfuric acid, (2) immersing it in formic acid, and (3) immersing it in potassium iodine meiodide solution. method, (4) method of immersion in sulfuric acid or hydrochloric acid and a mixed solution of sulfuric acid and hydrochloric acid, (5)
Various methods such as dipping in borofluoric acid and hydrofluoric acid can be employed, but among these etching treatments, etching with hydrochloric acid is preferable because it is superior in terms of the plating surface gloss and adhesion strength. Considering that the polyamide molded product in the etching solution has a particularly superior appearance compared to conventional molded products, has a gloss similar to that of a mirror, and has other properties such as adhesion strength, heat resistance, mechanical strength, and rigidity. It is extremely excellent in all aspects.

In addition, by specifying the average particle size and content of wollastonite and the relative viscosity with polyamide, the range of molding conditions can be expanded, and even if there are slight variations in molding conditions, the molded product of the present invention can be processed. It can always be obtained stably.

The present invention will be specifically described below using Examples and Comparative Examples. In the Examples and Comparative Examples, the molding conditions, the shape of the molded product, the plating method, and the performance evaluation method (surface gloss, adhesion strength) of the plated product were in accordance with the following methods.

・Molding conditions Molding machine: Meiki Seisakusho ・Model M-100 injection molding machine Cylinder temperature: 240X280X285X
2g5℃ (nozzle side) Injection pressure crab 30-50 Ks/c
d (gauge pressure) mold temperature 280-100℃ Molding cycle: 15see/15sse (injection/cooling) Molded product shape (flat plate) Length xsom, width IQQm, thickness 3mm (using side gate) *Electroplating Sample for determining surface gloss Copper plating thickness: 15μ, Nickel plating thickness: 28μ, Chrome plating thickness: 0.2μ Sample for measuring plating adhesion strength Copper plating thickness: Near 0
μ Adhesion Strength The peel strength (−) of the plated film was measured by cutting a rectangular shape with a width of 1 on the film surface of an electrical steel plated product (thickness: 70 μ) at an angle of 9001 and a peeling speed of −304 minutes.

Adhesion strength measurement point Adhesion strength often varies depending on the measurement location.

The larger the difference, the greater the variation in adhesion strength. In particular, the adhesion strength in the general area of the molded product may be extremely deteriorated in some cases, so the adhesion strength in the vicinity of the gate (from the gate to 30111) was measured.

Judgment of adhesion strength Judgment of surface gloss ◎: Reflects light like a mirror and has surface gloss equivalent to ABS resin plating.

Q: Although it is slightly worse than ABS resin plating, it can be used for practical purposes.

Δ: The surface is cloudy and reflects light diffusely.

×: The surface is pear-like and has no specularity at all.

(Average particle size: 1.6μ, injection loss 0
．． Pellets containing the amounts shown in Table 1 were molded under the molding conditions described above. The mechanical and thermal properties of the molded products before plating treatment (hereinafter referred to as unplated products) were evaluated using ASTM test pieces in a conventional manner.
The adhesion strength and surface gloss of the plated products (hereinafter referred to as plated products) were evaluated and are also listed in Table 1.

Table 1 As is clear from Table 1, when the wollastonite content is low, the adhesive strength and mechanical strength are low, and when the wollastonite content is high, the appearance becomes extremely poor.

Example-4/Comparative Example-3, 4 Nylon-6 (relative viscosity 2.50) was added with wollastonite (average particle size = 1.8 μ, ignition loss - 1.0 weight factor) and talc ( Average particle size -2,2
Pellets containing 40% by weight of unfired clay (average particle size = 1.9μ) and unfired clay (average particle size = 1.9μ) were molded according to a conventional method, and the plated molded products were evaluated. The results are shown in Table 2. Indicated.

Table 2 Examples 5-7/Comparative Examples 5-7 Nylon-6 (relative viscosity 2.45) wollastonite (ignition loss 〇, 3) with different average particle sizes
Pellets each containing 40% by weight were molded according to a conventional method, and the plated molded products were evaluated. The results are shown in Table 3.

Table 3 Examples 8 to 1O/Comparative Examples 8 to 10 Nylon-6C (relative viscosity 2.40) and wollastonite (average particle size = 2.0) with different ignition losses
Pellets containing 35% of μ) were molded according to a conventional method, and the plated molded products were evaluated, and the results are shown in Table 4.
It was shown to.

Table 4 Wollastonite on nylon-6 with different relative viscosities (ignition loss - 2.0 weight ta, average particle size - 1.8
Pellets with different amounts of .mu.) were molded according to a conventional method and plated molded products were evaluated, and the results are shown in Table 5.

Table-5 Examples 16-17/Comparative Examples 15-16 Pellets made of nylon-6 with different relative viscosities with different contents of wollastonite (ignition loss - 1,2 weight factor) and average particle size were prepared using a conventional method. The molded products molded and plated according to the method were evaluated and the results are shown in Table 6.

Table 6 Examples 18 to 21 Wollastonite (ignition loss) on polyamide
A pellet containing 3.0 weight factor, average particle diameter -2.3 μ) 40 weight factor was molded according to a conventional method, and the plated molded product was evaluated. The results are shown in Table 7.

Table-7

Claims (1)

[Scope of Claims] 1) A metal-plated polyamide molded product, in which the polyamide molded product excluding the metal-plated portion has an average particle size of 0.5.
~4.0μ, and the weight loss upon firing at 1000°C is 4.0μ.
When the relative viscosity of a metal-plated polyamide molded product characterized by containing 15 to 60 wt. A metal-plated polyamide molded product according to claim 1, characterized in that the product satisfies the following equation when the relative viscosity of the medium is V: Metal-plated polyamide molded product. 2.0≦V≦0.06172 + 2.9...
......---...4] The method according to claim 1, which contains wollastonite with an average particle size of 0.5 to 2.6 μm. Metal-plated polyamide molding. 5) Claim 1 in which the polyamide is nylon 6
Metal-plated polyamide molded article as described in Section 1.